OpenBSD Errata: November 29th, 2018 (smtpd)

Errata patches for OpenSMTPD have been released for OpenBSD 6.4.
The mail.mda and mail.lmtp delivery agents were not reporting temporary
failures correctly, causing smtpd to bounce messages in some cases where
it should have retried them.
Binary updates for the amd64, i386, and arm64 platforms are available
via the syspatch utility. Source code patches can be found on the errata
page:
https://www.openbsd.org/errata64.html
After patching, restart the smtpd service.